A slight shape difference influences an operating characteristic of a device in accordance with miniaturization of a semiconductor pattern, and therefore need for shape management is increased. Therefore, in a scanning electron microscope (SEM) for use in inspection and measurement of a semiconductor, high sensitivity and high precision are demanded more than before. Meanwhile, a form of a signal waveform has been changed in accordance with miniaturization of a pattern. In a case where a sample is irradiated with an electron beam, a greater amount of secondary electrons are emitted from a corner (edge) portion of a pattern in comparison with an amount of secondary electrons emitted from a flat portion. A shape is determined based on this difference between the emission amounts. In length measurement of a line, the length measurement is performed based on peaks of edges in both ends of the line. However, because a width of the line is decreased due to miniaturization, the peaks of the edges are overlapped and therefore cannot be separated. In view of this, characteristic signal detection using signal discrimination or the like is demanded.
In this case, emission distribution of secondary electrons obtained in a case where irradiation is performed with an electron beam is unchanged, and therefore it is important to separate detected secondary electrons. In order to separate detected signals, separation of secondary electrons based on an angle can be a solution. PTL 1 discloses a SEM including two detectors which discriminate and detect electrons (high angle electrons) passing through a track near an optical axis of an electron beam and electrons (low angle electrons) passing through a track relatively apart from the optical axis of the electron beam in order to form an image of a hole bottom with a high contrast on the basis of electrons emitted from a bottom of a deep hole such as a contact hole. PTLs 2 and 3 disclose a SEM including a secondary-electron deflector which controls a track of secondary electrons in order to make uniform detected signals in a plurality of detectors.